Method and device for transmitting block division information in image codec for security camera

ABSTRACT

The present invention relates to a method and device for transmitting block division information for efficient image coding in a video compression technique for a high-definition security camera. To this end, the present invention obtains block division information from a bitstream, determines the division form of an image by computing and predicting omitted information if there is omitted information in the obtained information, and performs video decoding in the unit of a divided block.

RELATED APPLICATIONS

This is a continuation of U.S. application Ser. No. 16/282,291 filedFeb. 21, 2019, which is a continuation application of the InternationalPatent Application Serial No. PCT/KR2016/010879, filed Sep. 29, 2016,which claims priority to the Korean Patent Application Serial No.10-2016-0105955, filed Aug. 22, 2016. Both of these applications areincorporated by reference herein in their entireties.

TECHNICAL FIELD

The present invention relates to a video encoding and decoding techniquein a high-quality video compression method and apparatus for a securitycamera, and more particularly, to a method and apparatus fortransmitting division information of a unit block of a video.

BACKGROUND

In recent years, there has been a growing demand for a variety ofdevices and systems for security, due to increasing social anxiety dueto crime such as indiscriminate crimes against unspecified persons,retaliatory crimes against certain targets, and crimes against sociallyvulnerable classes. In particular, security cameras (CCTV) can be usedas evidence for crime scenes or impression descriptions of criminals,thus demand for personal safety as well as national demand isincreasing. However, due to the limited conditions in transmission orstorage of acquired data, image quality deteriorates or there is a realproblem that can be saved as a low-quality image. In order to utilize avariety of security camera images, a high-quality compression methodcapable of storing a high-quality image with a low data amount isrequired.

In the video compression technique, generally, the encoding/decoding ofthe image is not performed on the whole image. The encoding/decoding ofthe image is performed by dividing the image into blocks of a sizesuitable for encoding/decoding. The coding performance may be improvedby the encoding/decoding unit of an appropriate size suitable for thecharacteristic of the image.

SUMMARY

It is an object of the present invention to provide a method andapparatus for transmitting information on a unit block forencoding/decoding of a high-quality image in a bitstream.

It is to be understood, however, that the technical problems of thepresent invention is not limited to the above-described technicalproblems, and other technical problems may exist.

As technical solutions for achieving the above object, an apparatus anda method for decoding an image according to one embodiment of thepresent invention comprises obtaining division information of a unitblock from a bitstream, determining division of a block using theobtained division information, and decoding the image on a divided blockbasis using the determined division information.

It is an object of the present invention to provide a method and anapparatus for performing the image encoding/decoding through anefficient transmission method of division information of a unit block inthe process of performing encoding/decoding of a block unit in order toimprove coding efficiency.

According to an embodiment of the present invention, the codingperformance may be improved by efficiently transmitting divisioninformation of a block to a decoder.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 illustrates a decoding apparatus according to an embodiment ofthe present invention.

FIG. 2 illustrates a division shape of a block according to anembodiment of the present invention.

FIGS. 3 and 4 are flowcharts illustrating a method of extractingdivision information of a block and performing block-based decodingusing the division information according to an embodiment of the presentinvention.

FIG. 5 is a flowchart illustrating a process of obtaining divisioninformation of a block according to an embodiment of the presentinvention.

DETAILED DESCRIPTION

Hereinafter, embodiments of the present invention will be described indetail with reference to the drawings attached hereto, so that thoseskilled in the art can easily carry out the present invention. Thepresent invention may, however, be embodied in many different forms andshould not be construed as limited to the embodiments set forth herein.In order to clearly illustrate the present invention, parts not relatedto the description are omitted in the drawings, and similar parts aredenoted by similar reference numerals throughout the specification.

Throughout this specification, when a part is referred to as being‘connected’ to another part, it includes not only a case where it isdirectly connected but also a case where the part is electricallyconnected with another part and there are other devices in between.

In addition, in the specification, when an element is referred to asbeing “comprising” an element, it is understood that the element mayfurther comprise other elements without excluding other elements as longas there is no contrary description.

The term “˜step” or “step of˜” used in the present specification doesnot imply a step for˜.

Also, the terms such as first, second, etc. may be used to describevarious components, but the components should not be limited by theterms. The terms are used only for the purpose of distinguishing onecomponent from another.

In addition, the components shown in the embodiments of the presentinvention are shown independently to represent different characteristicfunctions, and it does not mean that each component is composed ofseparate hardware or one software constituent unit. That is, eachconstituent unit is described separately for convenience of explanation,and at least two constituent units of constituent units may be combinedto form one constituent unit or one constituent unit may be divided intoa plurality of constituent units to perform a function. The integratedembodiments and the separate embodiments of each of these components arealso included in the scope of the present invention without departingfrom the essence of the present invention.

First, the terms used in the present application will be brieflydescribed as follows.

The video decoding apparatus may be a device included in the serverterminal such as a personal security camera, a private security system,a military security camera, a military security system, a personalcomputer (PC), a notebook computer, a portable multimedia player (PMP),a wireless communication terminal, a smart phone, a TV applicationserver, and a service server. The video decoding apparatus may bevarious devices including a user terminal such as various devices, acommunication device such as a wired/wireless communication network,Communication modem to perform communication etc., various programs forinter-prediction or intra-prediction or for decoding an image, a memoryfor storing data, and a microprocessor for calculating and controllingby executing a program.

In addition, an image encoded into a bitstream by an encoder may betransmitted in real time or in non-real time via a wired or wirelesscommunication network such as the internet, a local area wirelesscommunication network, a wireless LAN network, a WiBro network, a mobilecommunication network, or via a cable, Universal Serial Bus (USB), andthe like to an image decoding apparatus. The encoded image may bedecoded and restored into an image, and then reproduced.

In general, a moving picture may be composed of a series of pictures,and each picture may be divided into a coding unit such as a block. Itis to be understood that the term ‘picture’ described below may bereplaced with other terms having an equivalent meaning such as an image,a frame, etc. The term ‘coding unit’ may be replaced with other termshaving equivalent meanings such as a unit block, block, and the like.

Hereinafter, embodiments of the present invention will be described indetail with reference to the drawings. In the description of the presentinvention, duplicate descriptions will be omitted for the samecomponents.

FIG. 3 is a flowchart illustrating a method of extracting divisioninformation of a block and performing decoding in a block unit using thedivision information according to an embodiment of the presentinvention.

First, information on the division of a block is extracted from abitstream (310). According to an embodiment of the present invention,the division information of the block may include a flag indicatingwhether to divide the block, a shape of the divided block, a size of thedivided block, the minimum division size of the block, the maximum sizeof the block, the number of the division and the like. Also, accordingto the embodiment of the present invention as shown in FIG. 4, all ofthe division information may be extracted from the bitstream or only apart of the division information may be extracted from the bitstream ifonly a part of the division information is transmitted to a decodingapparatus. A part of the division information may not be signaled forcoding efficiency and may be predicted or calculated by the decoderwithout the extraction process from the bitstream in the decodingapparatus (411). The decoding apparatus determines, based on theinformation extracted from the bitstream and the calculated information,the division shape of the block to be decoded (320). The decodingapparatus performs decoding according to the division shape. In thiscase, the division information of the block such as the division sizeand shape of the block in each step of decoding may be different fromeach other. The division information may be derived, based on thepromise between the encoding apparatus and the decoding apparatus, bythe decoding apparatus or may be extracted from the bitstream.

Hereinafter, embodiments of the present invention will be described indetail with reference to the drawings attached hereto, so that thoseskilled in the art can easily carry out the present invention. Thepresent invention may, however, be embodied in many different forms andshould not be construed as limited to the embodiments set forth herein.In order to clearly illustrate the present invention, parts not relatedto the description are omitted in the drawings, and similar parts aredenoted by similar reference numerals throughout the specification.

Throughout this specification, when a part is referred to as being‘connected’ to another part, it includes not only a case where it isdirectly connected but also a case where the part is electricallyconnected with another part and there are other devices in between.

In addition, in the specification, when an element is referred to asbeing “comprising” an element, it is understood that the element mayfurther comprise other elements without excluding other elements as longas there is no contrary description.

The term “˜step” or “step of˜” used in the present specification doesnot imply a step for˜.

Also, the terms such as first, second, etc. may be used to describevarious components, but the components should not be limited by theterms. The terms are used only for the purpose of distinguishing onecomponent from another.

In addition, the components shown in the embodiments of the presentinvention are shown independently to represent different characteristicfunctions, and it does not mean that each component is composed ofseparate hardware or one software constituent unit. That is, eachconstituent unit is described separately for convenience of explanation,and at least two constituent units of constituent units may be combinedto form one constituent unit or one constituent unit may be divided intoa plurality of constituent units to perform a function. The integratedembodiments and the separate embodiments of each of these components arealso included in the scope of the present invention without departingfrom the essence of the present invention.

First, the terms used in the present application will be brieflydescribed as follows.

The video decoding apparatus may be a device included in the serverterminal such as a personal security camera, a private security system,a military security camera, a military security system, a personalcomputer (PC), a notebook computer, a portable multimedia player (PMP),a wireless communication terminal, a smart phone, a TV applicationserver, and a service server. The video decoding apparatus may bevarious devices including a user terminal such as various devices, acommunication device such as a wired/wireless communication network,Communication modem to perform communication etc., various programs forinter-prediction or intra-prediction or for decoding an image, a memoryfor storing data, and a microprocessor for calculating and controllingby executing a program.

In addition, an image encoded into a bitstream by an encoder may betransmitted in real time or in non-real time via a wired or wirelesscommunication network such as the internet, a local area wirelesscommunication network, a wireless LAN network, a WiBro network, a mobilecommunication network, or via a cable, Universal Serial Bus (USB), andthe like to an image decoding apparatus. The encoded image may bedecoded and restored into an image, and then reproduced.

In general, a moving picture may be composed of a series of pictures,and each picture may be divided into a coding unit such as a block. Itis to be understood that the term ‘picture’ described below may bereplaced with other terms having an equivalent meaning such as an image,a frame, etc. The term ‘coding unit’ may be replaced with other termshaving equivalent meanings such as a unit block, block, and the like.

Hereinafter, embodiments of the present invention will be described indetail with reference to the drawings. In the description of the presentinvention, duplicate descriptions will be omitted for the samecomponents.

FIG. 1 illustrates a decoding apparatus for performing image decoding ona block-by-block basis using division information of a block accordingto an embodiment of the present invention. The decoding apparatus mayinclude at least one of an entropy decoding unit 110, an inversequantization unit 120, an inverse transform unit 130, an interprediction unit 140, an intra prediction unit 150, an in-loop filterunit 160, or a reconstructed image storage unit 170.

The entropy decoding unit 110 decodes the input bitstream 100 andoutputs decoding information such as syntax elements and quantizedcoefficients. The output information may include division information ofa block on which decoding is performed. The division information may betransmitted in various forms. Signaling of the division information maybe omitted under certain conditions. The division information may bepredicted or calculated by the decoding apparatus. The inversequantization, inverse transform, inter prediction, intra prediction,motion compensation, and in-loop filtering may be performed on ablock-by-block basis, and the size and shape of blocks used in each stepmay be the same or different. Information such as a block size or ablock shape may be extracted from the bitstream through the divisioninformation or may be calculated or predicted using informationextracted from the bitstream.

The inverse quantization unit 120 and the inverse transformation unit130 receive the quantizated coefficient, perform inverse-quantizationand inverse-transform, and output a residual signal.

The inter prediction unit 140 performs motion compensation using amotion vector obtained from the bitstream and a reconstructed imagestored in the reconstructed image storage unit 170 to generate aprediction signal. The inter prediction unit 140 includes a step ofperforming motion compensation.

The intra prediction unit 150 generates a prediction signal of a currentblock by performing spatial prediction using pixel values of a decodedneighboring block adjacent to the current block to be decoded.

The prediction signals output from the inter prediction unit 140 and theintra prediction unit 150 are summed with the residual signal, and thereconstructed image generated through the summing is transmitted to thein-loop filter unit 160.

The reconstructed picture to which the filtering is applied in thein-loop filter unit 160 is stored in the reconstructed image storageunit 170 and may be used as a reference picture in the inter predictionunit 140.

FIG. 2 illustrates a division shape of a block according to anembodiment of the present invention. For the efficiency ofencoding/decoding, the encoding/decoding of the image is performed bydividing a block into a square or a rectangle as illustrated in thedrawing. Like the embodiment of the present invention, the divisioninformation of the drawing may be obtained from the bitstream. Thedivision information may be predicted or calculated in the decodingapparatus and may not be transmitted from the encoding apparatus.

An apparatus and method for decoding an image according to an embodimentof the present invention comprises the steps of obtaining divisioninformation of a unit block, determining division of a block using theobtained division information, and performing image decoding on adivided block basis. The division information may include informationrelating to whether or not to divide a block, division method, divisiontype, and division direction. The division information may be extracted,from the bitstream, in the form of flags.

An image decoding apparatus and method according to an embodiment of thepresent invention comprises extracting information on a maximum size anda minimum size of a unit block from a bitstream, extracting informationon the number of divisions, extracting information on a shape of thedivided block, determining division of a block using the obtaineddivision information, and performing image decoding by a block unitwhich determined based on the division information.

An apparatus and method for decoding an image according to an embodimentof the present invention comprises extracting division information of aunit block from a bitstream, and performing image decoding by a blockunit which determined based on the division information. The divisioninformation may be extracted, from the bitstream, in the form of a blockmode.

An apparatus and method for decoding an image according to an embodimentof the present invention may predict or calculate a minimum size of aunit block using a minimum unit of a prediction block and a minimum sizeinformation of a transform kernel. The division information may bepredicted, calculated, and used based on the predicted information in adecoding apparatus. The decoding apparatus comprises a step ofperforming image decoding by a divided block unit, by using the divisioninformation.

An apparatus and method for decoding an image according to an embodimentof the present invention may predict or calculate division informationof a current decoding block by using information of a neighboring blockor a reference image. An apparatus and method for decoding an imageaccording to an embodiment of the present invention comprises performingimage decoding by predicting or calculating the division information ina decoding apparatus, without extracting division information from thebitstream.

The division of the block is generally performed in a square or arectangle, but may also be a triangle, a polygon or an irregular shapeaccording to an embodiment of the invention.

FIG. 3 is a flowchart illustrating a method of extracting divisioninformation of a block and performing decoding in a block unit using thedivision information according to an embodiment of the presentinvention.

First, information on the division of a block is extracted from abitstream (310). According to an embodiment of the present invention,the division information of the block may include a flag indicatingwhether to divide the block, a shape of the divided block, a size of thedivided block, the minimum division size of the block, the maximum sizeof the block, the number of the division and the like. Also, accordingto the embodiment of the present invention as shown in FIG. 4, all ofthe division information may be extracted from the bitstream or only apart of the division information may be extracted from the bitstream ifonly a part of the division information is transmitted to a decodingapparatus. A part of the division information may not be signaled forcoding efficiency and may be predicted or calculated by the decoderwithout the extraction process from the bitstream in the decodingapparatus (411). The decoding apparatus determines, based on theinformation extracted from the bitstream and the calculated information,the division shape of the block to be decoded (320). The decodingapparatus performs decoding according to the division shape. In thiscase, the division information of the block such as the division sizeand shape of the block in each step of decoding may be different fromeach other. The division information may be derived, based on thepromise between the encoding apparatus and the decoding apparatus, bythe decoding apparatus or may be extracted from the bitstream.

FIG. 5 is a flowchart illustrating a process of determining a divisionshape of a block when division information of a block is extracted froma bitstream in the form of a flag in the embodiment of the presentinvention. First, information on the division type of the block isextracted among the division information of the block. The division typeof the block is determined to be a quad-tree division type or abinary-tree division type. The division type of the block is determinedbased on a flag. If the division type of the block is a quad-treedivision type, the block is divided based on a flag for determiningwhether to divide the block. With the progress of the division, each ofthe divided blocks has the flag for determining whether to divide theblock. If the information indicates that the block is not divided anymore, the division is stopped based on the information and the divisionshape of the block is determined. In the case of the binary-treedivision type, a flag for determining whether to divide the block basedon the binary-tree division and a flag for determining the direction ofthe division are required. Each of the divided block may have the saidinformation while proceeding the division of the block through thedirection of the division, that is, the horizontal or verticaldirection. If the information indicates that the division is no longervalid, the division is stopped based on the information and the divisionshape of the block is determined. It is also possible to divide a blockinto a mixture of a square and a non-square. In this case, each of thedivided blocks has flag information about the division shape and a flagindicating whether to divide the block.

In the embodiment of the present invention, some information may beomitted by the promise of the encoding and decoding apparatus in orderto efficiently transfer the division information of the block. Someinformation is not extracted from the bitstream, but may be determinedto be the pre-determined value or may be determined through predictionor calculation in the decoding apparatus. When the division of a blockis performed in a specific type of a quad-tree division or a binary-treedivision, the information on the division type of the block may beomitted. When the division of the block starts in a specific shape ofthe square or the non-square, flag information about the division typeof the block may be omitted in the block where the division is started.When the block has the same division information in a transform processand a motion compensation process, the minimum size of the divided blockcan not be smaller than the size of the transform kernel. Therefore, inthe block having the same size as the minimum size of the transformkernel, flag information on whether to divide the block may be omitted.

In addition, when there is a promise between the encoder and the decoderfor the minimum size of a block or when information about the minimumsize of the block is parsed in the bitstream, the block corresponding tothe minimum size does not have information about whether to divide theblock into sub-blocks. The block has a block shape of a square or anon-square. Even if the minimum size is not promised or transmitted, theminimum size of one side of a block can not be less than 1.

According to an embodiment of the present invention, when the maximumnumber of division times of a block is fixed or transmitted to a decoderthrough a bitstream, the divided blocks corresponding to the maximumnumber of division times do not have flag information about whether todivide into sub-blocks.

The present invention may be used in manufacturers such as broadcastingequipment manufacturing, terminal manufacturing, and industries relatedto original technology in video encoding/decoding related industries.

What is claimed is:
 1. A method for decoding a video signal, with adecoding apparatus, comprising: determining, with the decodingapparatus, a current block by dividing a coding block, wherein thedivision of the coding block is performed recursively based on both aquad-division and a binary-division, wherein the quad-division isperformed without extracting division information for the quad-divisionfrom a bitstream when a pre-determined condition is satisfied, whereinthe binary-division is performed by using a plurality of flags extractedfrom the bitstream, wherein the plurality of flags include a first flagfor indicating whether to use a binary-division type and a second flagfor specifying a division direction of the binary-division, and whereinthe second flag equal to a first value indicates a vertical directionwhile the second flag equal to a second value indicates a horizontaldirection; obtaining, with the decoding apparatus, a residual signal byperforming an inverse-quantization and an inverse-transform on quantizedcoefficients of the current block; generating, with the decodingapparatus, a prediction signal of the current block by performing anintra prediction based on reconstructed pixel values of a neighboringblock; and reconstructing, with the decoding apparatus, the currentblock using the residual signal and the prediction signal.
 2. The methodof claim 1, wherein the division information includes at least one of aflag indicating whether to divide the coding block, a shape of a dividedblock, a size of the divided block, a minimum division size, a maximumdivision size or a maximum number of the division times.
 3. The methodof claim 1, further comprising: dividing the current block obtainedbased on the binary-division into a plurality of sub-regions, wherein atleast one of the sub-regions has triangle shape.
 4. The method of claim1, wherein the inverse-quantization, the inverse-transform and the intraprediction are performed in units of blocks having a same size.
 5. Anon-transitory computer-readable storage medium having instructionsstored thereon that, when executed, cause one or more processor to:determining a current block by dividing a coding block, wherein thedivision of the coding block is performed recursively based on both aquad-division and a binary-division, wherein the quad-division isperformed without extracting division information for the quad-divisionfrom a bitstream when a pre-determined condition is satisfied, whereinthe binary-division is performed by using a plurality of flags extractedfrom the bitstream, wherein the plurality of flags include a first flagfor indicating whether to use a binary-division type and a second flagfor specifying a division direction of the binary-division, and whereinthe second flag equal to a first value indicates a vertical directionwhile the second flag equal to a second value indicates a horizontaldirection; obtaining a residual signal by performing aninverse-quantization and an inverse-transform on quantized coefficientsof the current block; generating a prediction signal of the currentblock by performing an intra prediction based on reconstructed pixelvalues of a neighboring block; and reconstructing the current blockusing the residual signal and the prediction signal.